package cn.itcast.netty.c4;

import jdk.nashorn.internal.ir.CallNode;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.charset.Charset;
import java.util.Iterator;

public class WriteServer {

    public static void main(String[] args) throws IOException {
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.configureBlocking(false);
        Selector selector = Selector.open();
        ssc.register(selector, SelectionKey.OP_ACCEPT);
        ssc.bind(new InetSocketAddress(8080));

        while (true) {
            selector.select();

            final Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()) {
                final SelectionKey key = iterator.next();
                iterator.remove();

                if (key.isAcceptable()) {
                    SocketChannel sc = ssc.accept();
                    sc.configureBlocking(false);
                    SelectionKey sckey = sc.register(selector, 0, null);
                    sckey.interestOps(SelectionKey.OP_READ);

                    //1 向客户端发送大量的数据
                    final StringBuilder sb = new StringBuilder();
                    for (int i = 0; i < 5000000; i++) {
                        sb.append("a");
                    }
                    ByteBuffer buffer = Charset.defaultCharset().encode(sb.toString());
                    //2 实际写入的字节数
                    int write = sc.write(buffer);
                    System.out.println(write);
                    // 3 是否有剩余内容
                    if (buffer.hasRemaining()) {
                        // 4 关注可写事件
                        sckey.interestOps(sckey.interestOps() + SelectionKey.OP_WRITE);

                        //5 将未写完的数据挂在scKey
                        sckey.attach(buffer);
                    }

                } else if (key.isWritable()) {

                    ByteBuffer buffer = (ByteBuffer) key.attachment();
                    SocketChannel sc = (SocketChannel) key.channel();
                    int write = sc.write(buffer);
                    System.out.println(write);
                    // 6 清理操作
                    if (!buffer.hasRemaining()) {
                        key.attach(null); //需要清除buffer
                        key.interestOps(key.interestOps() - SelectionKey.OP_WRITE); //不再关注可写是加你
                    }

                }

            }
        }

    }
}
